diff --git a/python-virtinst.spec b/python-virtinst.spec
index 7552b92..a4ad71e 100644
--- a/python-virtinst.spec
+++ b/python-virtinst.spec
@@ -17,7 +17,7 @@
 Summary: Python modules and utilities for installing virtual machines
 Name: python-%{appname}
 Version: 0.400.3
-Release: 11%{_extra_release}
+Release: 12%{_extra_release}
 Source0: http://virt-manager.org/download/sources/%{appname}/%{appname}-%{version}.tar.gz
 Patch1: %{appname}-%{version}-fix-virtimage-scratch.patch
 Patch2: %{appname}-%{version}-hostdev-libvirt-calls.patch
@@ -49,6 +49,8 @@ Patch15: %{appname}-%{version}-sasl-auth.patch
 Patch16: %{appname}-%{version}-windows-acpi.patch
 # Add CLI tests
 Patch17: %{appname}-%{version}-add-cli-test.patch
+# Ensure unknown OS detection doesn't break the install
+Patch18: %{appname}-%{version}-safe-os-detect.patch
 
 License: GPLv2+
 Group: Development/Libraries
@@ -93,6 +95,7 @@ and install new VMs) and virt-clone (clone an existing virtual machine).
 %patch15 -p1
 %patch16 -p1
 %patch17 -p1
+%patch18 -p1
 
 %build
 python setup.py build
@@ -128,6 +131,9 @@ rm -rf $RPM_BUILD_ROOT
 %{_bindir}/virt-convert
 
 %changelog
+* Thu Oct 22 2009 Cole Robinson <crobinso@redhat.com> - 0.400.3-12.fc11
+- Ensure unknown OS detection doesn't break the install
+
 * Mon Oct 05 2009 Cole Robinson <crobinso@redhat.com> - 0.400.3-11.fc11
 - Allow SASL auth (bz 484099)
 - Use ACPI for windows on KVM (bz 479977)
diff --git a/virtinst-0.400.3-safe-os-detect.patch b/virtinst-0.400.3-safe-os-detect.patch
new file mode 100644
index 0000000..148d72c
--- /dev/null
+++ b/virtinst-0.400.3-safe-os-detect.patch
@@ -0,0 +1,70 @@
+# HG changeset patch
+# User Cole Robinson <crobinso@redhat.com>
+# Date 1241726968 14400
+# Node ID db997572bdc8a8fc4c567fbf165f853167dfa462
+# Parent  9768e52d4d624f83853f7f23f85402c8a078eb6f
+Make sure autodetected OS type/variant are in the osdict.
+
+If not, log a message and set the values to None, rather than barf later
+down the line.
+
+diff -r 9768e52d4d62 -r db997572bdc8 virtinst/OSDistro.py
+--- a/virtinst/OSDistro.py	Thu May 07 15:50:06 2009 -0400
++++ b/virtinst/OSDistro.py	Thu May 07 16:09:28 2009 -0400
+@@ -28,6 +28,7 @@
+ import ConfigParser
+ 
+ import virtinst
++from virtinst.Guest import Guest
+ from virtinst import _util
+ from virtinst import _virtinst as _
+ 
+@@ -118,8 +119,9 @@
+         if iskernel is True:
+             # FIXME: We should probably do this for both kernel and boot
+             # disk?
++            os_type, os_variant = store.get_osdict_info()
+             return (store.acquireKernel(guest, fetcher, progresscb),
+-                    store.os_type, store.os_variant)
++                    os_type, os_variant)
+         elif iskernel is False:
+             return store.acquireBootDisk(fetcher, progresscb)
+         else:
+@@ -145,7 +147,7 @@
+     import urlgrabber
+     progress = urlgrabber.progress.BaseMeter()
+     store = _acquireMedia(None, None, location, progress, arch, "/var/tmp")
+-    return (store.os_type, store.os_variant)
++    return store.get_osdict_info()
+ 
+ 
+ def distroFromTreeinfo(fetcher, progresscb, uri, arch, vmtype=None,
+@@ -246,6 +248,28 @@
+             raise RuntimeError(_("Could not find boot.iso in %s tree." % \
+                                self.name))
+ 
++    def get_osdict_info(self):
++        """
++        Return (distro, variant) tuple, checking to make sure they are valid
++        osdict entries
++        """
++        if not self.os_type:
++            return (None, None)
++
++        if self.os_type not in Guest.list_os_types():
++            logging.debug("%s set os_type to %s, which is not in osdict." %
++                          (self, self.os_type))
++            return (None, None)
++
++        if (self.os_variant and
++            self.os_variant not in Guest.list_os_variants(self.os_type)):
++            logging.debug("%s set os_variant to %s, which is not in osdict"
++                          " for distro %s." %
++                          (self, self.os_variant, self.os_type))
++            return (self.os_type, None)
++
++        return (self.os_type, self.os_variant)
++
+     def _hasTreeinfo(self, fetcher, progresscb):
+         # all Red Hat based distros should have .treeinfo, perhaps others
+         # will in time